SEATTLE (AP)  A Seattle zoo has sent its two aging female elephants, Bamboo and Chai, on their long journey to a new home in Oklahoma City after a federal appeals court declined to block the transfer.

A flatbed truck carrying the elephants’ climate-controlled crates left the Woodland Park Zoo Wednesday evening on the 2,000-mile trip, expected to take about 40 hours.

Earlier Wednesday, a panel of the 9th U.S. Circuit Court of Appeals denied a motion by activists to stop the move to the Oklahoma City Zoo.

Activists have said the long trip could endanger the elephants’ health and that their quality of life in Oklahoma would be worse than in Seattle. The legal action was part of the broader debate about whether housing elephants in zoos is humane, with critics arguing the large animals need more space than zoos can provide. Activists wanted them sent to a sanctuary.

Bamboo is 48; Chai is 36.

Woodland Park Zoo President Deborah Jensen said in a statement that officials were grateful for the court’s decision and were focused on the elephants’ welfare.

“A team of our elephant experts, veterinarians and the transport consultant staff will accompany the truck,” zoo spokeswoman Gigi Allianic said in an email. “The trip will be straight through except to stop every few hours to check on the animals’ well-being and to provide food and change water.”

Two months of crate training for the elephants helped the loading go smoothly, she said.

The zoo “‘packed a trunk’ for our elephants,” said mammal curator Martin Ramirez. The “road trip” food included 660 pounds of hay and watermelon, cantaloupe and honeydew melon.

“Yes, we’re sad to see them go  like sending your kids off to college and saying goodbye  but we’re doing the right thing for Bamboo and Chai,” Allianic said. Zoo officials have said the elephants will be able to join a larger, multigenerational herd in Oklahoma City.

Alyne Fortgang, a co-founder of the Elephant Justice Project, joined other activists at the zoo when it was clear the move was imminent. Some of them wept.

“This is not a protest. We would do that Saturday, when it probably would more aptly be called a vigil,” she said. “This is not about us being heartbroken. This is about the elephants  our humanity and how we treat these other beings.”

She called it “a sad day for the citizens of Seattle.”

Woodland Park Zoo estimates it will cost $111,000 to ship the two elephants to Oklahoma City. They will be on a long-term loan.

The zoo has said the transfer will also give the pair more space. The zoo considered a number of U.S. zoos with Asian elephants before deciding the Oklahoma City Zoo was the best choice.

The Elephant Justice Project had asked the city of Seattle to block the move.

The Seattle City Council passed an ordinance in 2001 transferring the management and ownership of the zoo to the nonprofit Woodland Park Zoological Society. But Mayor Ed Murray has asked that the zoo consider sending the elephants to a sanctuary or a home where they would have more space and live in a warmer climate.